Radial piston machine

ABSTRACT

The invention relates to pistons, piston shoes and associated safety means in fluid handling devices including hydraulic or pneumatic pumps, motors and transmissions, wherein recesses for the reception of portions of the piston shoes are provided in a fluid handling body and the walls which are adjacent to the recesses serve to prevent the escape of piston shoes from the recesses, wherein convex and concave semispherical engagement surfaces are provided on the pistons and piston shoes and wherein piston stroke enlargement means and friction preventing means may be associated with the piston shoes and/or pistons or the fluid handling body.

D United States Patent 1191 1111 3,874,271 Eickmann Apr. 1, 1975 [54] RADIAL PISTON MACHINE FOREIGN PATENTS OR APPLICATIONS [761 lnvemorl Karl Eickmanfih 2420 Isshiki, 580.223 11/1924 France 91/498 Hayama-machi. Kanagawa-k n. 581,750 9/1958 Italy 91/492 Japan 1.101084 5/1961 Germany 1 417/273 1.254.200 4/1960 France 91/498 [221 1973 896,052 2/1945 France 91/492 121 Appl. No.: 322,086

Primary Etaminer-William L. Freeh Assistant Examiner-Gregory P'aul LaPointe [30] Foreign Apphcauon Priority Data Attorney, Agent, or Firm-Michael S. Striker Jan. 7. 1972 Austria 137/72 52 us. 01. 91/491 [57] ABSTRACT 151 1111. C1. F04b 1/06 The invention relates to P -1 Piston Shoes and 9589- [58] Field of Search 91/491-498, ciated safety means in fluid handling devices including 91 4 43 439; 417 273 hydraulic or pneumatic pumps, motors and transmissions, wherein recesses for the reception of portions of [56] R fere Ci d the piston shoes are provided in a fluid handling body UNITED STATES PATENTS and the walls which are adjacent to the recesses serve I to prevent the escape of piston shoes from the recesses, wherein convex and concave semispherical en- 8/194; Glasner gagement surfaces are provided on the pistons and pis- 511991460 8/1965 Bush ct 111.21: I: 11:: 91/494 Shoes and wherein Piston Stroke enlargement 3,223,046 12/1965 Eickmann 1 91/488 means and friction Preventing means y be associ- 3.274.946 9/1966 Simmons 91/486 at with h piston shoes nd/or piston or the fluid 3,628.425 12/1971 Morita 91/488 handling body. 3,650,180 3/1972 Gantschni' 91/488 3,663,125 5/1972 Freeman/7.? 91/498 9 Clam, 6 Drawmg Flgures PATENTEDAPR H915 3- Fig.2

Part

RADIAL PISTON MACHINE BACKGROUND OF THE INVENTION There are many known fluid handling devices which have reciprocating pistons in a fluid handling body for drawing a fluid into and for expelling fluid from the body. Such devices also have piston shoes which are associated with the pistons. Such fluid handling devices are disclosed, for example, in my US. Pat. Nos. 3,223,046; 3,270.685; 3.277.834; 3,304,883 and in many other patents.

However, in those devices the piston shoes slide along guide means at their axial ends and they were pivotally connected to the pistons.

The guides for the piston shoes create a certain amount of friction between the neighboring faces which reduces the efficiency of the device. The machining of the piston-piston shoe connection is complex and expensive and, most of all, the piston-piston shoe connection takes up space either on the piston or on the piston shoe, for an engagement means which holds the pivotable piston and piston shoe together. Therefore, only a portion of the crosssectional area of the piston can be utilized for transmitting force from the piston to the piston shoe or from the piston shoe to the piston during the high pressure stroke of the device. The other portion of the cross-sectional area of the piston is needed for the retaining means or the retaining member, which partially embraces either the piston shoe or the piston for keeping them together. If a piston shoe or the like has a cross-sectional area greater than that of the piston, its radial length must be increased which in turn reduces the stroke and thereby the power of the device having a fluid handling body ofa given diameter. The limited portion of the cross-sectional area ofthe piston can presently be used for the transmission of power from the shoe to the piston or from the piston to the shoe during a high pressure stroke reduces the maximum power transfer at the same ratio as the ratio of the cross-sectional area utilized for the power transfer to the cross-sectional area of the piston. Consequently the pressure which could be generated in the known devices is limited by the utilized cross-sectional area and therefore, the pressure and power output of conventional devices are limited.

SUMMARY OF THE INVENTION It is an object of the invention to overcome the drawbacks of the heretofore used fluid handling devices by reducing the friction, the machining problems and to increase the pressure, power and efficiency. The invention contemplates:

a. the provision of recesses in the fluid handling body for reception of all or parts of the respective piston shoes;

b. the provision of a self-centering seat on each piston shoe which may include a hollow cone for the reception of the respective piston;

c. the provision of substantially hemispherical convex and concave seats of constant radii on the pistons and piston shoes;

d. the provision of retaining wall means or wall members adjacent to the recesses of the fluid handling body for the prevention of escape of the piston shoes from the respective recesses;

e. the provision of spaces between the ends of the piston shoes and the respective walls for complete elimination of friction at the tangential, peripheral and axial ends of the piston shoes;

f. the provision of enlarged recesses for floating piston shoes each of which centers itself on the respective piston head for pivotal movement with respect thereto during the pressure stroke of the piston and piston shoe for the prevention of expensive and accurate machining ofa fixed piston shoe connection;

g. the provision of wall members on the fluid handling rotary body for partially embracing the ends of an associated rotary actuator member for the piston shoes for the purpose of lengthening the piston strokes and thereby a higher rate of fluid flow, greater power and high efficiency of the device;

h. the provision of an annular groove in the actuator member for partial reception of a wall member of the fluid handling body, again for the purpose of lengthening the piston stroke and of thereby increasing the power, the rate of fluid flow and effi ciency of the device;

i. the provision ofa recess extension radially inwardly into the fluid handling body beyond the adjacent end of the respective cylinder for the reception and movement of an extended portion of the piston shoe radially inwardly beyond the adjacent end of the respective cylinder in the fluid handling body to thus achieve a long piston stroke, a high rate of fluid flow, greater power and high efficiency to the device;

j. the provision of fluid receiving and fluid containing balancing recesses in the pistons and piston shoes. which recesses extend over more than 60 percent and, if desired, up to about percent of the crosssectional areas of the associated pistons in order to substantially reduce the friction between the pistons and the piston shoes as well as between the outer faces of the piston shoes and the actuator means to which the piston shoes conform for the further purpose of achieving a higher pressure and thereby a higher power output in a fluid handling device of a given size and flow-through volume whereby the power, efficiency and pressure of the fluid handling device are substantially increased.

The ability of the fluid handling device of the invention to achieve higher fluid pressures due to greater quantities of displaced fluid as a result of longer piston strokes, greater power and efficiency in a given size are not the only improvements because at the same time the device of the invention is simplified so that it is easier and less expensive to build and its parts can be massproduced whereby some of SUlCl'l parts may be produced simultaneously in a single operation.

Additional details and features of the invention will be explained in the following description of certain embodiments which are illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial sectional view of a fluid handling device which embodies one form of the invention;

FIG. 2 is a cross-sectional view of the structure shown in FIG. 1;

FIG. 3 is an axial sectional view of a fluid handling device which embodies another form of the invention;

FIG. 4 is a cross sectional sectional view of the structure shown in FIG. 3;

FIG. is a sectional view of portions of a modified piston and piston shoe; and

FIG. 6 is a fragmentary axial sectional view of a further embodiment of the fluid handling body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2 the fluid handling body 9 has cylinders 47 wherein the pistons 2 reciprocate during operation of the device. The pistons are associated to piston shoes 1 which engage the piston heads during the pressure strokes of the respective pistons. Each piston head is formed as a half ball or as a half mound bar with an axis normal to the axis of the piston. In any case the piston head face has a constant radius, about the same as the associated piston shoe seat of the piston shoe 1. Consequently the piston shoe has a seat face which conforms to the piston head at least during the high pressure stroke of the piston. The piston shoes seat face has therefore also a constant radius and thereby either the form of about a half hollow ball or of a half hollow cylinder. The seats of each piston head and of the associated piston shoe are complementary to each other. The piston shoe seat 44 may extend into a tapered, conical, or inclined face or faces serving the purpose of centering the piston shoe on the respective piston head, if-the piston and piston shoe are forced toward each other.

The fluid handling body 9 has recesses 4 for the reception of portions of or entire piston shoes. Securing walls 3 flank the recesses to prevent escape of the piston shoes. The piston shoes 1 have enlarged extensions 45 with walls 5 which would touch the walls 3 of the recesses 4 if the piston shoes would become separated from the respective pistons during rest or during a low pressure operation of the device. The walls 3, 5 prevent escape of piston shoes from the respective recesses 4. As soon as fluid pressure is applied to the outer end of a piston 2, the piston moves toward the associated piston shoe and abuts directly against the piston shoe seat 44 or against the aforementioned face, taper or cone and slides therelong until it reaches a position of smooth engagement between the seats of the piston shoe and the piston head. The piston shoes are secured in axial direction against escape from the recesses 4 by confining walls 29 and 31 of the housing. A space 46 is provided between the walls 5 of the elargements 45 and the walls 3 of the recess 4 as well as between the axial ends of the piston shoes 1 and the walls 29 and 31.

Thus, due to provision of the above described securing wall means 3, 29 and 31 the escape of a piston shoe from the corresponding recess 4 is prevented. The spaces 46 prevent contact between walls 3, 5, 29, 31 during each high pressure stroke of the device. If some friction is permissible, the space 46 can be narrowed accordingly. The piston shoes 1 have pressure balancing recesses 7 which receive fluid through passages 8 and prevent the generation of high friction between the inner faces of the piston shoes 1 and the outer face or guide face 6 of the actuator means 11. The actuator means 11 effects the high pressure strokes of the pistons 2 and piston shoes 1 when the actuator means 11 is actuated by the drive means 12 and key means 13. The pistons 2 perform intake strokes under the action of fluid supplied by supercharger pump means 17. An

inlet valve 14 and an exit valve 15 is associated with each cylinder 47 of the fluid handling device. Thus, there is provided an inlet valve 14 and an exit valve 15 for each recess 4 of the fluid handling device.

While in the embodiment of FIGS. 1 and 2 the body of the fluid handling drive is a stator, the body of the fluid handling device of FIGS. 3 and 4 is a rotor.

In FIGS. 3 and 4 the fluid handling rotor 40 is rotatable on the shaft 13 and is received in a housing 28 having end walls 29 and 32. Cylinders 26 are provided in the rotor 40 for the reception of portions of the pistons 2 Fluid is passed through the end wall 32 via ports 33 and 34. One of the ports 33, 34 is the inlet port and the other the outlet port. The fluid flows through passages 38 and 39 of a control body 36-37 into and out of the cylinders 26. The rotor 40 has recesses 23 for piston shoes 1. The piston shoes have outer faces 21 which slide along the inner face 22 of an actuator means 28 which compels successive pistons and shoes to perform inward strokes. The piston shoes perform outward strokes either by centrifugal force during rotation of the rotor 40 or by compressed fluid entering the cylinders 26 and 47. Walls 46 bounding the recesses 23 prevent the escape of piston shoes tangentially of the recesses because the piston shoe extensions 45 are so long that they cannot move over the walls 46 of the recesses 23. The escape of the piston shoes 1 axially and out of recesses 23 is prevented by the securing wall means 29 and 31 disposed at the axial ends ofthe recesses 23. The wall means 29 may have a thrust bearing 30 for the rotor 40 and the wall means 29 and 31 may have radial bearings for the shaft 13 and rotor 40. The piston shoes have outer recesses 41 for admission of fluid from the cylinders 26 through passages 8 of pistons 2. The cylinders 26 have walls 25 which extend to their outer ends for guiding and sealing the pistons 2.

An important feature of the device of FIGS. 3 and 4 is that a large piston stroke and thereby a high rate of fluid flow and big power is assured. This is assured by the extensions 24 which form part of the recesses 23 and extend radially inwardly into the rotor 40 beyond the outer ends 25 of the cylinders 26 for the reception of the inward extensions 92 of the piston shoes 1 so that the extensions 92 of the piston shoes can enter the rotor 40 beyond the outer ends of the cylinders 26. In order to demonstrate the difference between the provision and the absence of the extensions 24, the upper recess 23 in FIG. 4 is shown without such inwardly extending extension. Actually however, the upper recess 23 would also have the extension 24, because, otherwise, the stroke of the pistons could only be short and thereby the rate of flow and the power of the device reduced. The semispherical piston head 49 is complementary to the hollow semispherical piston shoe seat 48 and abuts thereagainst so that the force can be transmitted from the piston to the piston shoe or from the piston shoe to the piston, while at the same time the piston shoe 1 can pivot upon the piston head relative to the respective piston 2 during operation of the device while the outer face of the shoe 1 and its balancing recess 41 slide along the inner actuator face of the stationary or rotary actuator means (ring or housing) 28. The recess 41 is provided in the piston head to eliminate or reduce friction between the piston shoe and the housing. The piston shoe portion above the piston head is kept as short as possible in order to provide a long piston stroke and thereby a high rate of fluid flow.

The cross sections through the recesses 4, 23 and through the piston shoes 1 normal to the axes of the pistons 2 may be of cylindrical or rectangular configuration. Consequently the recesses 4 or 23 are either cylinders or cubes. In FIGS. 1 to 4 the recesses 4 and 23 are shown in the form of cubes, meaning axially extending rectangular recesses through the fluid handling 9 or rotor 40. This configuration is prefered, because it is less expensive in production than a cylindrical configuration. A cylindrical configuration requires individual production of each recess 4 or 23 while a rectangular recess 4 or 23 can be pressed or cut at the same time through a number of axially aligned and stacked fluid handling bodies 9 or 40. The outer configurations of a large number of piston shoes complementary to such rectangular recesses can be produced at the same time by pressing, material extrusion or drawing. These configurations make therefor the piston shoes especially inexpensive.

FIG. 5 shows that the fluid receiving and fluid containing pressure balancing recess 148 in the head of the piston 2 may have a cross-sectional area almost the size of the cross-sectional area of the piston 2. ln praxis the area of the recess 148 is about 60 to 90 percent of that of the piston 2. Thereby the friction between the piston 2 and the piston shoe 1 is very substantially reduced. Such large sizes of balancing recesses 148 of 90 percent of the cross-sectional area of the piston 2 can be achieved only by the novel forms of the piston 2 and piston shoe 1. The elimination of holding means between pistons 2 and piston shoes 1 by the arrangement of the invention renders it possible to use the whole cross-sectional area of the piston for the transfer of forces from piston to piston shoe or from piston shoe to piston, which was not possible to such an extent heretofore, because heretofore a portion of the crosssectional area of the piston head or of the piston shoe was needed for the provision of a holding means for keeping the piston connected with the piston shoe during the operation of the device.

The utilization of the whole cross-sectional area of the piston for the described power transfer by resorting to large balancing recesses 148 and 41 insures a very pronounced increase of the pressure fluid in the fluid handling device with little friction between the piston and the piston shoe. The pressure in actually built devices was increased to over 10,000 Psi with good efficiency and with accordingly increased power of the device without any increase in the size of the rotor, fluiding handling body or piston.

FIG. 6 shows that the fluid handling body 91 may be a rotor surrounded by a rotary actuator ring 28 however, the body 91 and ring 28 could also be stationary if so desired. The FIG. 6 further shows that the fluid handling body 91 may be a double or multi-cylinder group device for one or more flows of fluid through its cylinder groups 147 and 247. The recesses 23 for the reception of piston shoes 1 (not shown) are then flanked by walls 83 and 84 secured to the fluid handling body 91 and/or by a wall or walls 82 integral with the fluid handling body 91. In order to obtain a large piston stroke and thereby a high rate of flow the actuator ring 28 may be provided with an annular groove 81 for re ception of a portion of the wall 82 and the walls 83 and 84 may extend radially outwardly partially beyond the inner face of the actuator ring 28. Recesses or extensions can be provided radially on the fluid handling body 9, 40 or 91 or on the actuator means 11, 28 peripherally of the piston shoes 1 for preventing their escape out of the recesses 4 or 23 in response to very long piston strokes. The said extensions may then temporarily extend into said recesses. The latter are not shown in the figures because they may be provided in any suitable portion of the means whereon they are provided.

The fluid handling device of the invention produces a high pressure, insures long piston strokes, high rate of flow of fluid, good efficiency and great power and is easy to build, inexpensive in production and very reliable in operation for long periods of time because friction is eliminated or reduced to a considerable extent.

What is claimed is:

1. In a radial piston machine, a combination comprising a housing; a fluid handling body member provided in said housing and having substantially radially extending cylinders; an actuator member provided in said housing and having an endless guide surface, one of said members surrounding the other of said members; pistons reciprocably mounted in said cylinders and defining with said body member variable-volume working chambers remote from said guide surface, said chambers forming part of the respective cylinders and having inlets for admission and outlets for evacuation of a fluid medium; piston shoes associated with said pistons and slidable along said guide surface in response to rotation of one of said members relative to the other of said members to thereby reciprocate said pistons in the respective cylinders, at least a portion of each of said shoes having a polygonal cross sectional outline and said body member having polygonal recesses receiving said portions of said shoes with sufficient clearance to at least temporarily afford to said portions of said shoes the freedom of limited tilting movement in at least two different directions so as to enable said shoes to follow said endless guide surface of said actuator member while the machine is in operation, said pistons and said shoes being provided with normally abutting complementary curved surfaces having constant radii of curvature so as to enable said shoes to pivot on the respective pistons; and confining means for retaining said portions of said shoes in the respective recesses.

2. A combination as defined in claim 1, wherein said clearances suffice to allow said portions of said shoes to move with respect to said housing at least temporarily in the radial, axial and circumferential directions of said body member.

3. A combination as defined in claim 1, wherein said recesses and said portions of said shoes are rectangular, as considered in planes which are normal to the axes of the respective pistons.

4. A combination as defined in claim 1, wherein said portions constitute enlarged extensions of the respective piston shoes, as considered in the radial direction of the associated pistons.

5. A combination as defined in claim 1, wherein said curved surfaces are substantially hemispherical surfaces, one thereof being convex and the other thereof being concave and said concave surfaces having conical extensions.

6. A combination as defined in claim 1, wherein at least one of said complementary curved surfaces has a recess having a cross-sectional area slightly less than the cross-sectional area of the respective piston.

7. A combination as defined in claim 1, wherein the distance between said guide surface and said body member varies. as considered in the circumferential direction of said guide surfaces. and the maximum distance between said body member and said guide surface is less than the length of said portions of said shoes. as considered in the axial direction of said pistons. said length being greater than that of the maximum stroke of a piston.

8. A combination as defined in claim 1, wherein said 

1. In a radial piston machine, a combination comprising a housing; a fluid handling body member provided in said housing and having substantially radially extending cylinders; an actuator member provided in said housing and having an endless guide surface, one of said members surrounding the other of said members; pistons reciprocably mounted in said cylinders and defining with said body member variable-volume working chambers remote from said guide surface, said chambers forming part of the respective cylinders and having inlets for admission and outlets for evacuation of a fluid medium; piston shoes associated with said pistons and slidable along said guide surface in response to rotation of one of said members relative to the other of said members to thereby reciprocate said pistons in the rEspective cylinders, at least a portion of each of said shoes having a polygonal cross sectional outline and said body member having polygonal recesses receiving said portions of said shoes with sufficient clearance to at least temporarily afford to said portions of said shoes the freedom of limited tilting movement in at least two different directions so as to enable said shoes to follow said endless guide surface of said actuator member while the machine is in operation, said pistons and said shoes being provided with normally abutting complementary curved surfaces having constant radii of curvature so as to enable said shoes to pivot on the respective pistons; and confining means for retaining said portions of said shoes in the respective recesses.
 2. A combination as defined in claim 1, wherein said clearances suffice to allow said portions of said shoes to move with respect to said housing at least temporarily in the radial, axial and circumferential directions of said body member.
 3. A combination as defined in claim 1, wherein said recesses and said portions of said shoes are rectangular, as considered in planes which are normal to the axes of the respective pistons.
 4. A combination as defined in claim 1, wherein said portions constitute enlarged extensions of the respective piston shoes, as considered in the radial direction of the associated pistons.
 5. A combination as defined in claim 1, wherein said curved surfaces are substantially hemispherical surfaces, one thereof being convex and the other thereof being concave and said concave surfaces having conical extensions.
 6. A combination as defined in claim 1, wherein at least one of said complementary curved surfaces has a recess having a cross-sectional area slightly less than the cross-sectional area of the respective piston.
 7. A combination as defined in claim 1, wherein the distance between said guide surface and said body member varies, as considered in the circumferential direction of said guide surfaces, and the maximum distance between said body member and said guide surface is less than the length of said portions of said shoes, as considered in the axial direction of said pistons, said length being greater than that of the maximum stroke of a piston.
 8. A combination as defined in claim 1, wherein said fluid handling body has a ring-shaped wall adjacent to said recesses and said guide surface has an annular groove for said wall.
 9. A combination as defined in claim 1, wherein the depth of said recesses, as considered in the axial direction of said pistons, exceeds the length of maximum strokes of said pistons. 